include/linux/ftrace.h

   1 /*
   2  * Ftrace header.  For implementation details beyond the random comments
   3  * scattered below, see: Documentation/trace/ftrace-design.txt
   4  */
   5
   6 #ifndef _LINUX_FTRACE_H
   7 #define _LINUX_FTRACE_H
   8
   9 #include <linux/trace_clock.h>
  10 #include <linux/kallsyms.h>
  11 #include <linux/linkage.h>
  12 #include <linux/bitops.h>
  13 #include <linux/ptrace.h>
  14 #include <linux/ktime.h>
  15 #include <linux/sched.h>
  16 #include <linux/types.h>
  17 #include <linux/init.h>
  18 #include <linux/fs.h>
  19
  20 #include <asm/ftrace.h>
  21
  22 /*
  23  * If the arch supports passing the variable contents of
  24  * function_trace_op as the third parameter back from the
  25  * mcount call, then the arch should define this as 1.
  26  */
  27 #ifndef ARCH_SUPPORTS_FTRACE_OPS
  28 #define ARCH_SUPPORTS_FTRACE_OPS 0
  29 #endif
  30
  31 /*
  32  * If the arch's mcount caller does not support all of ftrace's
  33  * features, then it must call an indirect function that
  34  * does. Or at least does enough to prevent any unwelcomed side effects.
  35  */
  36 #if !ARCH_SUPPORTS_FTRACE_OPS
  37 # define FTRACE_FORCE_LIST_FUNC 1
  38 #else
  39 # define FTRACE_FORCE_LIST_FUNC 0
  40 #endif
  41
  42 /* Main tracing buffer and events set up */
  43 #ifdef CONFIG_TRACING
  44 void trace_init(void);
  45 #else
  46 static inline void trace_init(void) { }
  47 #endif
  48
  49 struct module;
  50 struct ftrace_hash;
  51
  52 #ifdef CONFIG_FUNCTION_TRACER
  53
  54 extern int ftrace_enabled;
  55 extern int
  56 ftrace_enable_sysctl(struct ctl_table *table, int write,
  57                      void __user *buffer, size_t *lenp,
  58                      loff_t *ppos);
  59
  60 struct ftrace_ops;
  61
  62 typedef void (*ftrace_func_t)(unsigned long ip, unsigned long parent_ip,
  63                               struct ftrace_ops *op, struct pt_regs *regs);
  64
  65 ftrace_func_t ftrace_ops_get_func(struct ftrace_ops *ops);
  66
  67 /*
  68  * FTRACE_OPS_FL_* bits denote the state of ftrace_ops struct and are
  69  * set in the flags member.
  70  * CONTROL, SAVE_REGS, SAVE_REGS_IF_SUPPORTED, RECURSION_SAFE, STUB and
  71  * IPMODIFY are a kind of attribute flags which can be set only before
  72  * registering the ftrace_ops, and can not be modified while registered.
  73  * Changing those attribute flags after regsitering ftrace_ops will
  74  * cause unexpected results.
  75  *
  76  * ENABLED - set/unset when ftrace_ops is registered/unregistered
  77  * DYNAMIC - set when ftrace_ops is registered to denote dynamically
  78  *           allocated ftrace_ops which need special care
  79  * CONTROL - set manualy by ftrace_ops user to denote the ftrace_ops
  80  *           could be controled by following calls:
  81  *             ftrace_function_local_enable
  82  *             ftrace_function_local_disable
  83  * SAVE_REGS - The ftrace_ops wants regs saved at each function called
  84  *            and passed to the callback. If this flag is set, but the
  85  *            architecture does not support passing regs
  86  *            (CONFIG_DYNAMIC_FTRACE_WITH_REGS is not defined), then the
  87  *            ftrace_ops will fail to register, unless the next flag
  88  *            is set.
  89  * SAVE_REGS_IF_SUPPORTED - This is the same as SAVE_REGS, but if the
  90  *            handler can handle an arch that does not save regs
  91  *            (the handler tests if regs == NULL), then it can set
  92  *            this flag instead. It will not fail registering the ftrace_ops
  93  *            but, the regs field will be NULL if the arch does not support
  94  *            passing regs to the handler.
  95  *            Note, if this flag is set, the SAVE_REGS flag will automatically
  96  *            get set upon registering the ftrace_ops, if the arch supports it.
  97  * RECURSION_SAFE - The ftrace_ops can set this to tell the ftrace infrastructure
  98  *            that the call back has its own recursion protection. If it does
  99  *            not set this, then the ftrace infrastructure will add recursion
 100  *            protection for the caller.
 101  * STUB   - The ftrace_ops is just a place holder.
 102  * INITIALIZED - The ftrace_ops has already been initialized (first use time
 103  *            register_ftrace_function() is called, it will initialized the ops)
 104  * DELETED - The ops are being deleted, do not let them be registered again.
 105  * ADDING  - The ops is in the process of being added.
 106  * REMOVING - The ops is in the process of being removed.
 107  * MODIFYING - The ops is in the process of changing its filter functions.
 108  * ALLOC_TRAMP - A dynamic trampoline was allocated by the core code.
 109  *            The arch specific code sets this flag when it allocated a
 110  *            trampoline. This lets the arch know that it can update the
 111  *            trampoline in case the callback function changes.
 112  *            The ftrace_ops trampoline can be set by the ftrace users, and
 113  *            in such cases the arch must not modify it. Only the arch ftrace
 114  *            core code should set this flag.
 115  * IPMODIFY - The ops can modify the IP register. This can only be set with
 116  *            SAVE_REGS. If another ops with this flag set is already registered
 117  *            for any of the functions that this ops will be registered for, then
 118  *            this ops will fail to register or set_filter_ip.
 119  * PID     - Is affected by set_ftrace_pid (allows filtering on those pids)
 120  */
 121 enum {
 122         FTRACE_OPS_FL_ENABLED                   = 1 << 0,
 123         FTRACE_OPS_FL_DYNAMIC                   = 1 << 1,
 124         FTRACE_OPS_FL_CONTROL                   = 1 << 2,
 125         FTRACE_OPS_FL_SAVE_REGS                 = 1 << 3,
 126         FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED    = 1 << 4,
 127         FTRACE_OPS_FL_RECURSION_SAFE            = 1 << 5,
 128         FTRACE_OPS_FL_STUB                      = 1 << 6,
 129         FTRACE_OPS_FL_INITIALIZED               = 1 << 7,
 130         FTRACE_OPS_FL_DELETED                   = 1 << 8,
 131         FTRACE_OPS_FL_ADDING                    = 1 << 9,
 132         FTRACE_OPS_FL_REMOVING                  = 1 << 10,
 133         FTRACE_OPS_FL_MODIFYING                 = 1 << 11,
 134         FTRACE_OPS_FL_ALLOC_TRAMP               = 1 << 12,
 135         FTRACE_OPS_FL_IPMODIFY                  = 1 << 13,
 136         FTRACE_OPS_FL_PID                       = 1 << 14,
 137 };
 138
 139 #ifdef CONFIG_DYNAMIC_FTRACE
 140 /* The hash used to know what functions callbacks trace */
 141 struct ftrace_ops_hash {
 142         struct ftrace_hash              *notrace_hash;
 143         struct ftrace_hash              *filter_hash;
 144         struct mutex                    regex_lock;
 145 };
 146 #endif
 147
 148 /*
 149  * Note, ftrace_ops can be referenced outside of RCU protection.
 150  * (Although, for perf, the control ops prevent that). If ftrace_ops is
 151  * allocated and not part of kernel core data, the unregistering of it will
 152  * perform a scheduling on all CPUs to make sure that there are no more users.
 153  * Depending on the load of the system that may take a bit of time.
 154  *
 155  * Any private data added must also take care not to be freed and if private
 156  * data is added to a ftrace_ops that is in core code, the user of the
 157  * ftrace_ops must perform a schedule_on_each_cpu() before freeing it.
 158  */
 159 struct ftrace_ops {
 160         ftrace_func_t                   func;
 161         struct ftrace_ops               *next;
 162         unsigned long                   flags;
 163         void                            *private;
 164         ftrace_func_t                   saved_func;
 165         int __percpu                    *disabled;
 166 #ifdef CONFIG_DYNAMIC_FTRACE
 167         int                             nr_trampolines;
 168         struct ftrace_ops_hash          local_hash;
 169         struct ftrace_ops_hash          *func_hash;
 170         struct ftrace_ops_hash          old_hash;
 171         unsigned long                   trampoline;
 172         unsigned long                   trampoline_size;
 173 #endif
 174 };
 175
 176 /*
 177  * Type of the current tracing.
 178  */
 179 enum ftrace_tracing_type_t {
 180         FTRACE_TYPE_ENTER = 0, /* Hook the call of the function */
 181         FTRACE_TYPE_RETURN,     /* Hook the return of the function */
 182 };
 183
 184 /* Current tracing type, default is FTRACE_TYPE_ENTER */
 185 extern enum ftrace_tracing_type_t ftrace_tracing_type;
 186
 187 /*
 188  * The ftrace_ops must be a static and should also
 189  * be read_mostly.  These functions do modify read_mostly variables
 190  * so use them sparely. Never free an ftrace_op or modify the
 191  * next pointer after it has been registered. Even after unregistering
 192  * it, the next pointer may still be used internally.
 193  */
 194 int register_ftrace_function(struct ftrace_ops *ops);
 195 int unregister_ftrace_function(struct ftrace_ops *ops);
 196 void clear_ftrace_function(void);
 197
 198 /**
 199  * ftrace_function_local_enable - enable controlled ftrace_ops on current cpu
 200  *
 201  * This function enables tracing on current cpu by decreasing
 202  * the per cpu control variable.
 203  * It must be called with preemption disabled and only on ftrace_ops
 204  * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
 205  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 206  */
 207 static inline void ftrace_function_local_enable(struct ftrace_ops *ops)
 208 {
 209         if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
 210                 return;
 211
 212         (*this_cpu_ptr(ops->disabled))--;
 213 }
 214
 215 /**
 216  * ftrace_function_local_disable - enable controlled ftrace_ops on current cpu
 217  *
 218  * This function enables tracing on current cpu by decreasing
 219  * the per cpu control variable.
 220  * It must be called with preemption disabled and only on ftrace_ops
 221  * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
 222  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 223  */
 224 static inline void ftrace_function_local_disable(struct ftrace_ops *ops)
 225 {
 226         if (WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL)))
 227                 return;
 228
 229         (*this_cpu_ptr(ops->disabled))++;
 230 }
 231
 232 /**
 233  * ftrace_function_local_disabled - returns ftrace_ops disabled value
 234  *                                  on current cpu
 235  *
 236  * This function returns value of ftrace_ops::disabled on current cpu.
 237  * It must be called with preemption disabled and only on ftrace_ops
 238  * registered with FTRACE_OPS_FL_CONTROL. If called without preemption
 239  * disabled, this_cpu_ptr will complain when CONFIG_DEBUG_PREEMPT is enabled.
 240  */
 241 static inline int ftrace_function_local_disabled(struct ftrace_ops *ops)
 242 {
 243         WARN_ON_ONCE(!(ops->flags & FTRACE_OPS_FL_CONTROL));
 244         return *this_cpu_ptr(ops->disabled);
 245 }
 246
 247 extern void ftrace_stub(unsigned long a0, unsigned long a1,
 248                         struct ftrace_ops *op, struct pt_regs *regs);
 249
 250 #else /* !CONFIG_FUNCTION_TRACER */
 251 /*
 252  * (un)register_ftrace_function must be a macro since the ops parameter
 253  * must not be evaluated.
 254  */
 255 #define register_ftrace_function(ops) ({ 0; })
 256 #define unregister_ftrace_function(ops) ({ 0; })
 257 static inline int ftrace_nr_registered_ops(void)
 258 {
 259         return 0;
 260 }
 261 static inline void clear_ftrace_function(void) { }
 262 static inline void ftrace_kill(void) { }
 263 #endif /* CONFIG_FUNCTION_TRACER */
 264
 265 #ifdef CONFIG_STACK_TRACER
 266 extern int stack_tracer_enabled;
 267 int
 268 stack_trace_sysctl(struct ctl_table *table, int write,
 269                    void __user *buffer, size_t *lenp,
 270                    loff_t *ppos);
 271 #endif
 272
 273 struct ftrace_func_command {
 274         struct list_head        list;
 275         char                    *name;
 276         int                     (*func)(struct ftrace_hash *hash,
 277                                         char *func, char *cmd,
 278                                         char *params, int enable);
 279 };
 280
 281 #ifdef CONFIG_DYNAMIC_FTRACE
 282
 283 int ftrace_arch_code_modify_prepare(void);
 284 int ftrace_arch_code_modify_post_process(void);
 285
 286 struct dyn_ftrace;
 287
 288 void ftrace_bug(int err, struct dyn_ftrace *rec);
 289
 290 struct seq_file;
 291
 292 struct ftrace_probe_ops {
 293         void                    (*func)(unsigned long ip,
 294                                         unsigned long parent_ip,
 295                                         void **data);
 296         int                     (*init)(struct ftrace_probe_ops *ops,
 297                                         unsigned long ip, void **data);
 298         void                    (*free)(struct ftrace_probe_ops *ops,
 299                                         unsigned long ip, void **data);
 300         int                     (*print)(struct seq_file *m,
 301                                          unsigned long ip,
 302                                          struct ftrace_probe_ops *ops,
 303                                          void *data);
 304 };
 305
 306 extern int
 307 register_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 308                               void *data);
 309 extern void
 310 unregister_ftrace_function_probe(char *glob, struct ftrace_probe_ops *ops,
 311                                 void *data);
 312 extern void
 313 unregister_ftrace_function_probe_func(char *glob, struct ftrace_probe_ops *ops);
 314 extern void unregister_ftrace_function_probe_all(char *glob);
 315
 316 extern int ftrace_text_reserved(const void *start, const void *end);
 317
 318 extern int ftrace_nr_registered_ops(void);
 319
 320 bool is_ftrace_trampoline(unsigned long addr);
 321
 322 /*
 323  * The dyn_ftrace record's flags field is split into two parts.
 324  * the first part which is '0-FTRACE_REF_MAX' is a counter of
 325  * the number of callbacks that have registered the function that
 326  * the dyn_ftrace descriptor represents.
 327  *
 328  * The second part is a mask:
 329  *  ENABLED - the function is being traced
 330  *  REGS    - the record wants the function to save regs
 331  *  REGS_EN - the function is set up to save regs.
 332  *  IPMODIFY - the record allows for the IP address to be changed.
 333  *
 334  * When a new ftrace_ops is registered and wants a function to save
 335  * pt_regs, the rec->flag REGS is set. When the function has been
 336  * set up to save regs, the REG_EN flag is set. Once a function
 337  * starts saving regs it will do so until all ftrace_ops are removed
 338  * from tracing that function.
 339  */
 340 enum {
 341         FTRACE_FL_ENABLED       = (1UL << 31),
 342         FTRACE_FL_REGS          = (1UL << 30),
 343         FTRACE_FL_REGS_EN       = (1UL << 29),
 344         FTRACE_FL_TRAMP         = (1UL << 28),
 345         FTRACE_FL_TRAMP_EN      = (1UL << 27),
 346         FTRACE_FL_IPMODIFY      = (1UL << 26),
 347 };
 348
 349 #define FTRACE_REF_MAX_SHIFT    26
 350 #define FTRACE_FL_BITS          6
 351 #define FTRACE_FL_MASKED_BITS   ((1UL << FTRACE_FL_BITS) - 1)
 352 #define FTRACE_FL_MASK          (FTRACE_FL_MASKED_BITS << FTRACE_REF_MAX_SHIFT)
 353 #define FTRACE_REF_MAX          ((1UL << FTRACE_REF_MAX_SHIFT) - 1)
 354
 355 #define ftrace_rec_count(rec)   ((rec)->flags & ~FTRACE_FL_MASK)
 356
 357 struct dyn_ftrace {
 358         unsigned long           ip; /* address of mcount call-site */
 359         unsigned long           flags;
 360         struct dyn_arch_ftrace  arch;
 361 };
 362
 363 int ftrace_force_update(void);
 364 int ftrace_set_filter_ip(struct ftrace_ops *ops, unsigned long ip,
 365                          int remove, int reset);
 366 int ftrace_set_filter(struct ftrace_ops *ops, unsigned char *buf,
 367                        int len, int reset);
 368 int ftrace_set_notrace(struct ftrace_ops *ops, unsigned char *buf,
 369                         int len, int reset);
 370 void ftrace_set_global_filter(unsigned char *buf, int len, int reset);
 371 void ftrace_set_global_notrace(unsigned char *buf, int len, int reset);
 372 void ftrace_free_filter(struct ftrace_ops *ops);
 373
 374 int register_ftrace_command(struct ftrace_func_command *cmd);
 375 int unregister_ftrace_command(struct ftrace_func_command *cmd);
 376
 377 enum {
 378         FTRACE_UPDATE_CALLS             = (1 << 0),
 379         FTRACE_DISABLE_CALLS            = (1 << 1),
 380         FTRACE_UPDATE_TRACE_FUNC        = (1 << 2),
 381         FTRACE_START_FUNC_RET           = (1 << 3),
 382         FTRACE_STOP_FUNC_RET            = (1 << 4),
 383 };
 384
 385 /*
 386  * The FTRACE_UPDATE_* enum is used to pass information back
 387  * from the ftrace_update_record() and ftrace_test_record()
 388  * functions. These are called by the code update routines
 389  * to find out what is to be done for a given function.
 390  *
 391  *  IGNORE           - The function is already what we want it to be
 392  *  MAKE_CALL        - Start tracing the function
 393  *  MODIFY_CALL      - Stop saving regs for the function
 394  *  MAKE_NOP         - Stop tracing the function
 395  */
 396 enum {
 397         FTRACE_UPDATE_IGNORE,
 398         FTRACE_UPDATE_MAKE_CALL,
 399         FTRACE_UPDATE_MODIFY_CALL,
 400         FTRACE_UPDATE_MAKE_NOP,
 401 };
 402
 403 enum {
 404         FTRACE_ITER_FILTER      = (1 << 0),
 405         FTRACE_ITER_NOTRACE     = (1 << 1),
 406         FTRACE_ITER_PRINTALL    = (1 << 2),
 407         FTRACE_ITER_DO_HASH     = (1 << 3),
 408         FTRACE_ITER_HASH        = (1 << 4),
 409         FTRACE_ITER_ENABLED     = (1 << 5),
 410 };
 411
 412 void arch_ftrace_update_code(int command);
 413
 414 struct ftrace_rec_iter;
 415
 416 struct ftrace_rec_iter *ftrace_rec_iter_start(void);
 417 struct ftrace_rec_iter *ftrace_rec_iter_next(struct ftrace_rec_iter *iter);
 418 struct dyn_ftrace *ftrace_rec_iter_record(struct ftrace_rec_iter *iter);
 419
 420 #define for_ftrace_rec_iter(iter)               \
 421         for (iter = ftrace_rec_iter_start();    \
 422              iter;                              \
 423              iter = ftrace_rec_iter_next(iter))
 424
 425
 426 int ftrace_update_record(struct dyn_ftrace *rec, int enable);
 427 int ftrace_test_record(struct dyn_ftrace *rec, int enable);
 428 void ftrace_run_stop_machine(int command);
 429 unsigned long ftrace_location(unsigned long ip);
 430 unsigned long ftrace_get_addr_new(struct dyn_ftrace *rec);
 431 unsigned long ftrace_get_addr_curr(struct dyn_ftrace *rec);
 432
 433 extern ftrace_func_t ftrace_trace_function;
 434
 435 int ftrace_regex_open(struct ftrace_ops *ops, int flag,
 436                   struct inode *inode, struct file *file);
 437 ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
 438                             size_t cnt, loff_t *ppos);
 439 ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 440                              size_t cnt, loff_t *ppos);
 441 int ftrace_regex_release(struct inode *inode, struct file *file);
 442
 443 void __init
 444 ftrace_set_early_filter(struct ftrace_ops *ops, char *buf, int enable);
 445
 446 /* defined in arch */
 447 extern int ftrace_ip_converted(unsigned long ip);
 448 extern int ftrace_dyn_arch_init(void);
 449 extern void ftrace_replace_code(int enable);
 450 extern int ftrace_update_ftrace_func(ftrace_func_t func);
 451 extern void ftrace_caller(void);
 452 extern void ftrace_regs_caller(void);
 453 extern void ftrace_call(void);
 454 extern void ftrace_regs_call(void);
 455 extern void mcount_call(void);
 456
 457 void ftrace_modify_all_code(int command);
 458
 459 #ifndef FTRACE_ADDR
 460 #define FTRACE_ADDR ((unsigned long)ftrace_caller)
 461 #endif
 462
 463 #ifndef FTRACE_GRAPH_ADDR
 464 #define FTRACE_GRAPH_ADDR ((unsigned long)ftrace_graph_caller)
 465 #endif
 466
 467 #ifndef FTRACE_REGS_ADDR
 468 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 469 # define FTRACE_REGS_ADDR ((unsigned long)ftrace_regs_caller)
 470 #else
 471 # define FTRACE_REGS_ADDR FTRACE_ADDR
 472 #endif
 473 #endif
 474
 475 /*
 476  * If an arch would like functions that are only traced
 477  * by the function graph tracer to jump directly to its own
 478  * trampoline, then they can define FTRACE_GRAPH_TRAMP_ADDR
 479  * to be that address to jump to.
 480  */
 481 #ifndef FTRACE_GRAPH_TRAMP_ADDR
 482 #define FTRACE_GRAPH_TRAMP_ADDR ((unsigned long) 0)
 483 #endif
 484
 485 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 486 extern void ftrace_graph_caller(void);
 487 extern int ftrace_enable_ftrace_graph_caller(void);
 488 extern int ftrace_disable_ftrace_graph_caller(void);
 489 #else
 490 static inline int ftrace_enable_ftrace_graph_caller(void) { return 0; }
 491 static inline int ftrace_disable_ftrace_graph_caller(void) { return 0; }
 492 #endif
 493
 494 /**
 495  * ftrace_make_nop - convert code into nop
 496  * @mod: module structure if called by module load initialization
 497  * @rec: the mcount call site record
 498  * @addr: the address that the call site should be calling
 499  *
 500  * This is a very sensitive operation and great care needs
 501  * to be taken by the arch.  The operation should carefully
 502  * read the location, check to see if what is read is indeed
 503  * what we expect it to be, and then on success of the compare,
 504  * it should write to the location.
 505  *
 506  * The code segment at @rec->ip should be a caller to @addr
 507  *
 508  * Return must be:
 509  *  0 on success
 510  *  -EFAULT on error reading the location
 511  *  -EINVAL on a failed compare of the contents
 512  *  -EPERM  on error writing to the location
 513  * Any other value will be considered a failure.
 514  */
 515 extern int ftrace_make_nop(struct module *mod,
 516                            struct dyn_ftrace *rec, unsigned long addr);
 517
 518 /**
 519  * ftrace_make_call - convert a nop call site into a call to addr
 520  * @rec: the mcount call site record
 521  * @addr: the address that the call site should call
 522  *
 523  * This is a very sensitive operation and great care needs
 524  * to be taken by the arch.  The operation should carefully
 525  * read the location, check to see if what is read is indeed
 526  * what we expect it to be, and then on success of the compare,
 527  * it should write to the location.
 528  *
 529  * The code segment at @rec->ip should be a nop
 530  *
 531  * Return must be:
 532  *  0 on success
 533  *  -EFAULT on error reading the location
 534  *  -EINVAL on a failed compare of the contents
 535  *  -EPERM  on error writing to the location
 536  * Any other value will be considered a failure.
 537  */
 538 extern int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr);
 539
 540 #ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
 541 /**
 542  * ftrace_modify_call - convert from one addr to another (no nop)
 543  * @rec: the mcount call site record
 544  * @old_addr: the address expected to be currently called to
 545  * @addr: the address to change to
 546  *
 547  * This is a very sensitive operation and great care needs
 548  * to be taken by the arch.  The operation should carefully
 549  * read the location, check to see if what is read is indeed
 550  * what we expect it to be, and then on success of the compare,
 551  * it should write to the location.
 552  *
 553  * The code segment at @rec->ip should be a caller to @old_addr
 554  *
 555  * Return must be:
 556  *  0 on success
 557  *  -EFAULT on error reading the location
 558  *  -EINVAL on a failed compare of the contents
 559  *  -EPERM  on error writing to the location
 560  * Any other value will be considered a failure.
 561  */
 562 extern int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 563                               unsigned long addr);
 564 #else
 565 /* Should never be called */
 566 static inline int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
 567                                      unsigned long addr)
 568 {
 569         return -EINVAL;
 570 }
 571 #endif
 572
 573 /* May be defined in arch */
 574 extern int ftrace_arch_read_dyn_info(char *buf, int size);
 575
 576 extern int skip_trace(unsigned long ip);
 577 extern void ftrace_module_init(struct module *mod);
 578
 579 extern void ftrace_disable_daemon(void);
 580 extern void ftrace_enable_daemon(void);
 581 #else /* CONFIG_DYNAMIC_FTRACE */
 582 static inline int skip_trace(unsigned long ip) { return 0; }
 583 static inline int ftrace_force_update(void) { return 0; }
 584 static inline void ftrace_disable_daemon(void) { }
 585 static inline void ftrace_enable_daemon(void) { }
 586 static inline void ftrace_release_mod(struct module *mod) {}
 587 static inline void ftrace_module_init(struct module *mod) {}
 588 static inline __init int register_ftrace_command(struct ftrace_func_command *cmd)
 589 {
 590         return -EINVAL;
 591 }
 592 static inline __init int unregister_ftrace_command(char *cmd_name)
 593 {
 594         return -EINVAL;
 595 }
 596 static inline int ftrace_text_reserved(const void *start, const void *end)
 597 {
 598         return 0;
 599 }
 600 static inline unsigned long ftrace_location(unsigned long ip)
 601 {
 602         return 0;
 603 }
 604
 605 /*
 606  * Again users of functions that have ftrace_ops may not
 607  * have them defined when ftrace is not enabled, but these
 608  * functions may still be called. Use a macro instead of inline.
 609  */
 610 #define ftrace_regex_open(ops, flag, inod, file) ({ -ENODEV; })
 611 #define ftrace_set_early_filter(ops, buf, enable) do { } while (0)
 612 #define ftrace_set_filter_ip(ops, ip, remove, reset) ({ -ENODEV; })
 613 #define ftrace_set_filter(ops, buf, len, reset) ({ -ENODEV; })
 614 #define ftrace_set_notrace(ops, buf, len, reset) ({ -ENODEV; })
 615 #define ftrace_free_filter(ops) do { } while (0)
 616
 617 static inline ssize_t ftrace_filter_write(struct file *file, const char __user *ubuf,
 618                             size_t cnt, loff_t *ppos) { return -ENODEV; }
 619 static inline ssize_t ftrace_notrace_write(struct file *file, const char __user *ubuf,
 620                              size_t cnt, loff_t *ppos) { return -ENODEV; }
 621 static inline int
 622 ftrace_regex_release(struct inode *inode, struct file *file) { return -ENODEV; }
 623
 624 static inline bool is_ftrace_trampoline(unsigned long addr)
 625 {
 626         return false;
 627 }
 628 #endif /* CONFIG_DYNAMIC_FTRACE */
 629
 630 /* totally disable ftrace - can not re-enable after this */
 631 void ftrace_kill(void);
 632
 633 static inline void tracer_disable(void)
 634 {
 635 #ifdef CONFIG_FUNCTION_TRACER
 636         ftrace_enabled = 0;
 637 #endif
 638 }
 639
 640 /*
 641  * Ftrace disable/restore without lock. Some synchronization mechanism
 642  * must be used to prevent ftrace_enabled to be changed between
 643  * disable/restore.
 644  */
 645 static inline int __ftrace_enabled_save(void)
 646 {
 647 #ifdef CONFIG_FUNCTION_TRACER
 648         int saved_ftrace_enabled = ftrace_enabled;
 649         ftrace_enabled = 0;
 650         return saved_ftrace_enabled;
 651 #else
 652         return 0;
 653 #endif
 654 }
 655
 656 static inline void __ftrace_enabled_restore(int enabled)
 657 {
 658 #ifdef CONFIG_FUNCTION_TRACER
 659         ftrace_enabled = enabled;
 660 #endif
 661 }
 662
 663 /* All archs should have this, but we define it for consistency */
 664 #ifndef ftrace_return_address0
 665 # define ftrace_return_address0 __builtin_return_address(0)
 666 #endif
 667
 668 /* Archs may use other ways for ADDR1 and beyond */
 669 #ifndef ftrace_return_address
 670 # ifdef CONFIG_FRAME_POINTER
 671 #  define ftrace_return_address(n) __builtin_return_address(n)
 672 # else
 673 #  define ftrace_return_address(n) 0UL
 674 # endif
 675 #endif
 676
 677 #define CALLER_ADDR0 ((unsigned long)ftrace_return_address0)
 678 #define CALLER_ADDR1 ((unsigned long)ftrace_return_address(1))
 679 #define CALLER_ADDR2 ((unsigned long)ftrace_return_address(2))
 680 #define CALLER_ADDR3 ((unsigned long)ftrace_return_address(3))
 681 #define CALLER_ADDR4 ((unsigned long)ftrace_return_address(4))
 682 #define CALLER_ADDR5 ((unsigned long)ftrace_return_address(5))
 683 #define CALLER_ADDR6 ((unsigned long)ftrace_return_address(6))
 684
 685 #ifdef CONFIG_IRQSOFF_TRACER
 686   extern void time_hardirqs_on(unsigned long a0, unsigned long a1);
 687   extern void time_hardirqs_off(unsigned long a0, unsigned long a1);
 688 #else
 689   static inline void time_hardirqs_on(unsigned long a0, unsigned long a1) { }
 690   static inline void time_hardirqs_off(unsigned long a0, unsigned long a1) { }
 691 #endif
 692
 693 #ifdef CONFIG_PREEMPT_TRACER
 694   extern void trace_preempt_on(unsigned long a0, unsigned long a1);
 695   extern void trace_preempt_off(unsigned long a0, unsigned long a1);
 696 #else
 697 /*
 698  * Use defines instead of static inlines because some arches will make code out
 699  * of the CALLER_ADDR, when we really want these to be a real nop.
 700  */
 701 # define trace_preempt_on(a0, a1) do { } while (0)
 702 # define trace_preempt_off(a0, a1) do { } while (0)
 703 #endif
 704
 705 #ifdef CONFIG_FTRACE_MCOUNT_RECORD
 706 extern void ftrace_init(void);
 707 #else
 708 static inline void ftrace_init(void) { }
 709 #endif
 710
 711 /*
 712  * Structure that defines an entry function trace.
 713  */
 714 struct ftrace_graph_ent {
 715         unsigned long func; /* Current function */
 716         int depth;
 717 };
 718
 719 /*
 720  * Structure that defines a return function trace.
 721  */
 722 struct ftrace_graph_ret {
 723         unsigned long func; /* Current function */
 724         unsigned long long calltime;
 725         unsigned long long rettime;
 726         /* Number of functions that overran the depth limit for current task */
 727         unsigned long overrun;
 728         int depth;
 729 };
 730
 731 /* Type of the callback handlers for tracing function graph*/
 732 typedef void (*trace_func_graph_ret_t)(struct ftrace_graph_ret *); /* return */
 733 typedef int (*trace_func_graph_ent_t)(struct ftrace_graph_ent *); /* entry */
 734
 735 #ifdef CONFIG_FUNCTION_GRAPH_TRACER
 736
 737 /* for init task */
 738 #define INIT_FTRACE_GRAPH               .ret_stack = NULL,
 739
 740 /*
 741  * Stack of return addresses for functions
 742  * of a thread.
 743  * Used in struct thread_info
 744  */
 745 struct ftrace_ret_stack {
 746         unsigned long ret;
 747         unsigned long func;
 748         unsigned long long calltime;
 749         unsigned long long subtime;
 750         unsigned long fp;
 751 };
 752
 753 /*
 754  * Primary handler of a function return.
 755  * It relays on ftrace_return_to_handler.
 756  * Defined in entry_32/64.S
 757  */
 758 extern void return_to_handler(void);
 759
 760 extern int
 761 ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth,
 762                          unsigned long frame_pointer);
 763
 764 /*
 765  * Sometimes we don't want to trace a function with the function
 766  * graph tracer but we want them to keep traced by the usual function
 767  * tracer if the function graph tracer is not configured.
 768  */
 769 #define __notrace_funcgraph             notrace
 770
 771 /*
 772  * We want to which function is an entrypoint of a hardirq.
 773  * That will help us to put a signal on output.
 774  */
 775 #define __irq_entry              __attribute__((__section__(".irqentry.text")))
 776
 777 /* Limits of hardirq entrypoints */
 778 extern char __irqentry_text_start[];
 779 extern char __irqentry_text_end[];
 780
 781 #define FTRACE_NOTRACE_DEPTH 65536
 782 #define FTRACE_RETFUNC_DEPTH 50
 783 #define FTRACE_RETSTACK_ALLOC_SIZE 32
 784 extern int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 785                                 trace_func_graph_ent_t entryfunc);
 786
 787 extern bool ftrace_graph_is_dead(void);
 788 extern void ftrace_graph_stop(void);
 789
 790 /* The current handlers in use */
 791 extern trace_func_graph_ret_t ftrace_graph_return;
 792 extern trace_func_graph_ent_t ftrace_graph_entry;
 793
 794 extern void unregister_ftrace_graph(void);
 795
 796 extern void ftrace_graph_init_task(struct task_struct *t);
 797 extern void ftrace_graph_exit_task(struct task_struct *t);
 798 extern void ftrace_graph_init_idle_task(struct task_struct *t, int cpu);
 799
 800 static inline int task_curr_ret_stack(struct task_struct *t)
 801 {
 802         return t->curr_ret_stack;
 803 }
 804
 805 static inline void pause_graph_tracing(void)
 806 {
 807         atomic_inc(&current->tracing_graph_pause);
 808 }
 809
 810 static inline void unpause_graph_tracing(void)
 811 {
 812         atomic_dec(&current->tracing_graph_pause);
 813 }
 814 #else /* !CONFIG_FUNCTION_GRAPH_TRACER */
 815
 816 #define __notrace_funcgraph
 817 #define __irq_entry
 818 #define INIT_FTRACE_GRAPH
 819
 820 static inline void ftrace_graph_init_task(struct task_struct *t) { }
 821 static inline void ftrace_graph_exit_task(struct task_struct *t) { }
 822 static inline void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) { }
 823
 824 static inline int register_ftrace_graph(trace_func_graph_ret_t retfunc,
 825                           trace_func_graph_ent_t entryfunc)
 826 {
 827         return -1;
 828 }
 829 static inline void unregister_ftrace_graph(void) { }
 830
 831 static inline int task_curr_ret_stack(struct task_struct *tsk)
 832 {
 833         return -1;
 834 }
 835
 836 static inline void pause_graph_tracing(void) { }
 837 static inline void unpause_graph_tracing(void) { }
 838 #endif /* CONFIG_FUNCTION_GRAPH_TRACER */
 839
 840 #ifdef CONFIG_TRACING
 841
 842 /* flags for current->trace */
 843 enum {
 844         TSK_TRACE_FL_TRACE_BIT  = 0,
 845         TSK_TRACE_FL_GRAPH_BIT  = 1,
 846 };
 847 enum {
 848         TSK_TRACE_FL_TRACE      = 1 << TSK_TRACE_FL_TRACE_BIT,
 849         TSK_TRACE_FL_GRAPH      = 1 << TSK_TRACE_FL_GRAPH_BIT,
 850 };
 851
 852 static inline void set_tsk_trace_trace(struct task_struct *tsk)
 853 {
 854         set_bit(TSK_TRACE_FL_TRACE_BIT, &tsk->trace);
 855 }
 856
 857 static inline void clear_tsk_trace_trace(struct task_struct *tsk)
 858 {
 859         clear_bit(TSK_TRACE_FL_TRACE_BIT, &tsk->trace);
 860 }
 861
 862 static inline int test_tsk_trace_trace(struct task_struct *tsk)
 863 {
 864         return tsk->trace & TSK_TRACE_FL_TRACE;
 865 }
 866
 867 static inline void set_tsk_trace_graph(struct task_struct *tsk)
 868 {
 869         set_bit(TSK_TRACE_FL_GRAPH_BIT, &tsk->trace);
 870 }
 871
 872 static inline void clear_tsk_trace_graph(struct task_struct *tsk)
 873 {
 874         clear_bit(TSK_TRACE_FL_GRAPH_BIT, &tsk->trace);
 875 }
 876
 877 static inline int test_tsk_trace_graph(struct task_struct *tsk)
 878 {
 879         return tsk->trace & TSK_TRACE_FL_GRAPH;
 880 }
 881
 882 enum ftrace_dump_mode;
 883
 884 extern enum ftrace_dump_mode ftrace_dump_on_oops;
 885 extern int tracepoint_printk;
 886
 887 extern void disable_trace_on_warning(void);
 888 extern int __disable_trace_on_warning;
 889
 890 #ifdef CONFIG_PREEMPT
 891 #define INIT_TRACE_RECURSION            .trace_recursion = 0,
 892 #endif
 893
 894 #else /* CONFIG_TRACING */
 895 static inline void  disable_trace_on_warning(void) { }
 896 #endif /* CONFIG_TRACING */
 897
 898 #ifndef INIT_TRACE_RECURSION
 899 #define INIT_TRACE_RECURSION
 900 #endif
 901
 902 #ifdef CONFIG_FTRACE_SYSCALLS
 903
 904 unsigned long arch_syscall_addr(int nr);
 905
 906 #endif /* CONFIG_FTRACE_SYSCALLS */
 907
 908 #endif /* _LINUX_FTRACE_H */